A lithosphere-scale structural model of the Barents Sea and Kara Sea region

P. Klitzke,J. Sippel,J. I. Faleide,M. Scheck-Wenderoth

doi:10.5194/se-6-153-2015

Abstract

Abstract. We introduce a regional 3-D structural model of the Barents Sea and Kara Sea region which is the first to combine information on the sediments and the crystalline crust as well as the configuration of the lithospheric mantle. Therefore, we have integrated all available geological and geophysical data, including interpreted seismic refraction and reflection data, seismological data, geological maps and previously published 3-D models into one consistent model. This model resolves four major megasequence boundaries (earliest Eocene, mid-Cretaceous, mid-Jurassic and mid-Permian) the top crystalline crust, the Moho and a newly calculated lithosphere–asthenosphere boundary (LAB). The thickness distributions of the corresponding main megasequences delineate five major subdomains (the northern Kara Sea, the southern Kara Sea, the eastern Barents Sea, the western Barents Sea and the oceanic domain comprising the Norwegian–Greenland Sea and the Eurasia Basin). Relating the subsidence histories of these subdomains to the structure of the deeper crust and lithosphere sheds new light on possible causative basin forming mechanisms that we discuss. The depth configuration of the newly calculated LAB and the seismic velocity configuration of the upper mantle correlate with the younger history of this region. The western Barents Sea is underlain by a thinned lithosphere (80 km) resulting from multiple Phanerozoic rifting phases and/or the opening of the NE Atlantic from Paleocene/Eocene times on. Notably, the northwestern Barents Sea and Svalbard are underlain by thinnest continental lithosphere (60 km) and a low-velocity/hot upper mantle that correlates spatially with a region where late Cenozoic uplift was strongest. As opposed to this, the eastern Barents Sea is underlain by a thicker lithosphere (~ 110–150 km) and a high-velocity/density anomaly in the lithospheric mantle. This anomaly, in turn, correlates with an area where only little late Cenozoic uplift/erosion was observed.

Highlights

Though of increasing economic relevance, intra-continental basins are poorly understood in terms of processes controlling their evolution (Allen and Allen, 2013; Cloetingh and Burov, 2011; Gac et al, 2013; Heine et al, 2008)
According to the depth differences between the bathymetry/topography and the earliest Eocene surface, the thickness distribution of the earliest Eocene present sediments show thickness maxima mostly restricted to the oceanic domain whereas significant continental deposits of this age are restricted to the southwesternmost Barents Sea (Fig. 4a)
It has to be noted that the age of basal sediments within the pre-mid-Permian megasequence varies distinctively laterally beneath the Barents Sea and Kara Sea region according to the onset of subsidence as outlined in the geological setting

Summary

Introduction

Though of increasing economic relevance, intra-continental basins are poorly understood in terms of processes controlling their evolution (Allen and Allen, 2013; Cloetingh and Burov, 2011; Gac et al, 2013; Heine et al, 2008). Essential progress can be made by integrated 3-D models Such models can be used as a base for structural analysis and to constrain the distribution of physical properties (i.e. density and temperature) and their impact on different processes. The Barents Sea and Kara Sea region is situated in such an intra-continental setting bordered by the ancient East European Craton in the southeast and two young passive margins in the north and in the west (Fig. 1). This region has experienced a manifold tectonic history involving multiple orogenies, episodes of intense subsidence and young continental break-up. Due to the assumed potential for hydrocarbon resources, the geodynamically complex setting of the Barents Sea and Kara Sea

Objectives

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Discussion

Conclusion